U.S. patent number 9,086,058 [Application Number 13/378,424] was granted by the patent office on 2015-07-21 for method for the natural-draught cooling of a solar concentration plant.
This patent grant is currently assigned to Abengoa Solar New Technologies, S.A.. The grantee listed for this patent is Jose Barragan Jimenez, Elena Garcia Ramirez, Rafael Olavarria Rodriguez-Arango. Invention is credited to Jose Barragan Jimenez, Elena Garcia Ramirez, Rafael Olavarria Rodriguez-Arango.
United States Patent |
9,086,058 |
Olavarria Rodriguez-Arango ,
et al. |
July 21, 2015 |
Method for the natural-draught cooling of a solar concentration
plant
Abstract
Method for the natural-draught cooling of a high-concentration
thermoelectric solar plant that includes a central receiver or
tower with a heliostat field, wherein the tower is used as a
natural-draught cooling tower. The steam originating from the
turbine will be made to circulate through a series of condensers
located at the base of the tower, where said condensers condense
the steam therein and discharge the condensation heat to the
atmosphere. The fluid responsible for this heat exchange is the air
at ambient temperature at the base of the tower. Once condensed,
the steam is pumped back towards the receiver so that it can be
re-used as a heat-transfer fluid. The cooling air travels up
through the tower and exits through the highest part thereof. The
plant can be used to reduce not only its own electricity
consumption, but also water consumption.
Inventors: |
Olavarria Rodriguez-Arango;
Rafael (Seville, ES), Garcia Ramirez; Elena
(Seville, ES), Barragan Jimenez; Jose (Seville,
ES) |
Applicant: |
Name |
City |
State |
Country |
Type |
Olavarria Rodriguez-Arango; Rafael
Garcia Ramirez; Elena
Barragan Jimenez; Jose |
Seville
Seville
Seville |
N/A
N/A
N/A |
ES
ES
ES |
|
|
Assignee: |
Abengoa Solar New Technologies,
S.A. (Seville, ES)
|
Family
ID: |
43355918 |
Appl.
No.: |
13/378,424 |
Filed: |
June 18, 2010 |
PCT
Filed: |
June 18, 2010 |
PCT No.: |
PCT/ES2010/000270 |
371(c)(1),(2),(4) Date: |
February 12, 2012 |
PCT
Pub. No.: |
WO2010/146202 |
PCT
Pub. Date: |
December 23, 2010 |
Prior Publication Data
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|
|
|
Document
Identifier |
Publication Date |
|
US 20120132403 A1 |
May 31, 2012 |
|
Foreign Application Priority Data
|
|
|
|
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Jun 19, 2009 [ES] |
|
|
200901459 |
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F03G
6/065 (20130101); F03G 6/06 (20130101); F03G
6/045 (20130101); F03G 6/003 (20130101); Y02E
10/46 (20130101); Y02E 10/465 (20130101) |
Current International
Class: |
F28D
15/02 (20060101); F03G 6/06 (20060101); F03G
6/00 (20060101); F03G 6/04 (20060101) |
Field of
Search: |
;60/641.8-641.15,527 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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2945969 |
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May 1981 |
|
DE |
|
10248068 |
|
May 2004 |
|
DE |
|
2000669 |
|
Dec 2008 |
|
EP |
|
2222838 |
|
Feb 2005 |
|
ES |
|
55142979 |
|
Nov 1980 |
|
JP |
|
2007073008 |
|
Jun 2007 |
|
WO |
|
WO 2007104080 |
|
Sep 2007 |
|
WO |
|
2008153922 |
|
Dec 2008 |
|
WO |
|
Other References
Torres, T. et al. "Cooling Systems for Thermoelectric Plants",
Informacion Tecnologica , 2003, vol. 14, No. 2, p. 36-38. English
Abstract provided. cited by applicant .
International Preliminary Report on Patentability of
PCT/ES2010/000270 issued on Aug. 2, 2011, 10 pages. Translation
included. cited by applicant.
|
Primary Examiner: Bomberg; Kenneth
Assistant Examiner: Mian; Shafiq
Attorney, Agent or Firm: Kilpatrick Townsend & Stockton
LLP
Claims
The invention claimed is:
1. A method for natural-draught cooling of a solar concentration
plant, comprising: circulating a heat-transfer fluid through an
evaporator located at a highest part of a solar tower; heating the
heat-transfer fluid by reflecting solar radiation on to the
evaporator with heliostats, and to produce saturated steam;
circulating the saturated steam from the evaporator through a drum,
and separating liquid from the saturated steam; circulating the
steam from the drum to a superheater, and increasing the
temperature of the steam by reflecting solar radiation reflected on
the superheater with the heliostats; circulating the steam from the
superheater through a turbine, connected to a generator and
producing electricity with the turbine; circulating the steam from
the turbine through conduits of a condenser installed in a base of
the solar tower; cooling and condensing the steam from the turbine
with the condenser using ambient air flowing through the condenser
and condensing the steam, the temperature of said air rising upon
absorbing heat by said air from the condenser and becoming heated
air; flowing said heated air up from the condenser and through the
tower towards the evaporator and the superheater in the solar
tower, further heating said air with heat from the evaporator and
the superheater; and discharging said heated air from the solar
tower to the atmosphere through the highest part of the solar
tower.
2. The method for natural-draught cooling of a solar concentration
plant according to claim 1, further comprising: pumping a portion
of the steam from the drum to a storage system, and passing the
steam through a valve for regulating pressure at a storage system
entrance.
3. The method for natural-draught cooling of a solar concentration
plant according to claim 1, further comprising: pumping the
condensed heat-transfer fluid from the condenser towards a
condensate storage tank; and raising the condensed heat-transfer
fluid stored in the condensate storage tank towards the evaporator
by a tank pump when additional heat-transfer fluid is required in
the evaporator.
4. A solar concentration plant, comprising: a solar tower
including: an evaporator located at a highest part of the solar
tower, said evaporator configured to allow circulation, and heating
of a heat-transfer fluid at into saturated steam, a drum downstream
from the evaporator configured to separate liquid from the
saturated steam in the heat-transfer fluid coming from the
evaporator, said drum having a first exit for the liquid and a
second exit for steam, and a superheater located at a highest part
of the solar tower, said superheater located downstream from the
second exit of the drum and configured to allow circulation of the
steam from the drum and increase the temperature of the steam from
the drum; a plurality of heliostats directed to: the evaporator to
heat by solar radiation the heat-transfer fluid circulating through
the evaporator, and the superheater to heat by solar radiation the
steam circulating through the superheater; a turbine downstream
from the superheater, said turbine configured to be moved by the
steam from the superheater; and a condenser downstream from the
turbine installed in a base of the solar tower, wherein the solar
tower further includes a heated air flow path from the condenser
towards the evaporator mad the superheater, the heated air flow
path including an outlet for discharging heated air from the solar
tower to the atmosphere through the highest part of the solar
tower, the condenser including a plurality of conduits configured
to allow circulation of steam from the turbine, the condenser
configured to cool and condense the steam from the turbine is
cooled and condensed due to a cooling effect of ambient air and
flowing through the condenser to condense the heat-transfer fluid,
wherein the temperature of said ambient air, is increased by
absorption of heat from the condenser conduits such that the to
become heated air, flowing up through the heated air flow path of
the solar tower from the base of the solar tower towards the
evaporator and the superheater, wherein the heated air is
discharged from the solar tower to the atmosphere, and wherein the
heated air is further heated by heat of the evaporator and the
superheater, the flow of said heated air rising through the heated
air flow path of the solar tower after extending a cooling effect
to the condenser.
5. The solar concentration plant of claim 4, further comprising: a
condensate storage tank to store condensed heat-transfer fluid; a
condenser pump to pump the condensed heat-transfer fluid from the
condenser to the condensate storage tank; and a tank pump to pump
the condensed heat-transfer fluid from the condensate storage tank
to the evaporator.
Description
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for the natural-draught
cooling of the steam originating from the turbine of a solar
concentration plant placed on tower technology.
BACKGROUND OF THE INVENTION
Within high solar concentration plants we can distinguish Stirling
disks, parabolic trough collectors and the technology discussed
herein, central receiver technology.
Central receiver systems consist of a heliostat field, made up of
mirrors with a large surface area (40-125 m.sup.2 per unit) called
sun-tracking heliostats, which reflect the direct solar radiation
incident upon one or several central receiver devices installed on
the highest part of a very high tower. These receiver devices are
usually found housed in cavities "excavated" in the tower
itself.
Concentrated solar radiation heats a fluid inside the receiver, the
thermal energy of which can subsequently be used to generate
electricity.
At present, water/steam technology is that most frequently used in
central receiver systems, using both saturated and superheated
steam as a heat-transfer fluid.
Therefore, these types of thermoelectric solar energy tower plants
require a location with guaranteed availability of two resources:
high solar irradiance and sufficient water supply. In general,
those areas with high irradiance indices are areas where water
supply is limited. To this end, in the search for more efficient
plants with solar receiver devices with the least possible water
consumption, the envisaged invention is intended for recirculating
and saving the greatest possible amount of water with the lowest
possible in-plant electricity consumption.
At present, conventional thermal power generation plants operate in
the following manner: the heliostats reflect the solar radiation
towards the receiver devices installed on the highest part of the
tower, whereupon said energy evaporates a fluid and the steam is
pumped towards a turbine to produce electricity and, at the outlet
of said turbine, water is recovered from the steam, which is still
at a high temperature. To this end, the steam that exits the
turbine is redirected towards a condenser. Mains water circulates
through said condenser at a temperature lower than that of the
steam, in such a manner that the steam releases its heat into the
mains water, condensing and enabling pumping thereof in order to
re-circulate it back towards the receiver device.
The mains water that circulates through the condenser to cool the
steam flows out at a temperature higher than that at which it
flowed thereinto. In order to re-use this water in the condenser
circuit, we must lower the temperature thereof. To this end,
cooling towers are used wherein circulation is forced by means of
large fans which allow the circulation of air and heat exchange
between said air and water. The temperature of the hot water coming
from the condensation circuit is lowered in these cooling towers by
transferring heat and matter to the air circulating therein.
A heat transfer medium called "fill pack" is used to improve the
air/water contact. Water enters the tower through the upper part
thereof and is evenly distributed over the fill pack using sprays.
In this manner, optimum contact between water and atmospheric air
is achieved.
The fill pack serves to increase water/air exchange time and
surface area. Once the water/air contact has been achieved, heat
from the water is released into the air. This is due to two
mechanisms: heat transfer by convection and water-to-air steam
transfer, with the consequent cooling of the water by
evaporation.
In heat transfer by convection, heat flows towards the air that
surrounds the water due to the difference in temperature between
the two fluids.
The evaporation cooling rate is significant in cooling towers,
approximately 90% being due to the diffusion phenomenon. When air
comes into contact with water, a thin film of saturated moist air
is formed on the film of water that descends through the fill pack.
This is due to the fact that partial water vapour pressure on the
film of air is greater than that of the moist air that circulates
through the tower, whereupon water vapour is released
(evaporation). This body of evaporated water extracts latent
vaporisation heat from the liquid itself. Said latent heat is
released into the air, cooling the water and raising air
temperature.
These previously envisaged systems have several drawbacks such as
the electricity consumption generated by the use of fans in the
cooling towers and the high degree of water consumption
required.
In order to reduce electricity consumption in conventional thermal
plants, so-called natural-draught or hyperbolic draught cooling is
used.
The air flowing through the natural-draught tower is mainly due to
the difference in density between the cold inflowing air and warm
outflowing air. The air expelled by the column is lighter than the
ambient air and a draught is created by means of the chimney
effect, thereby eliminating the need for mechanical fans.
The difference in speeds between the wind circulating at ground
level and the wind circulating through the highest part of the
chimney also help to establish the air flow. For both reasons,
natural-draught towers must be high and must also have a large
cross-section to facilitate the movement of ascendant air. These
towers have low maintenance costs and are highly recommended for
cooling large quantities of water. The average speed of the air
flowing through the tower is usually comprised between 1-2 m/s. In
these types of natural-draught towers, highly compact "fill packs"
are not used, due to the fact that airflow resistance must be as
small as possible.
As mentioned earlier, these towers are commonly used in thermal
plants, where tower construction requires considerable investment
but is compensated with less electricity consumption.
With regard to water consumption, it cannot be reduced, due to
which these types of plants are normally located in areas with a
guaranteed water supply.
DESCRIPTION OF THE INVENTION
The invention being proposed is a method for cooling a
high-concentration thermoelectric solar plant having a central
receiver or tower with a heliostat field, wherein the tower is used
as a natural-draught cooling tower. This plant will enable a
reduction in both internal electricity consumption and water
consumption, in such a manner that it can be installed in arid
regions, such as deserts, which are highly favourable areas for
solar energy due to their high number of daylight hours but where,
up until now, installation had been impossible due to their limited
water resources.
The solar plant of the invention proposes, for cooling thereof, a
tower surrounded by a heliostat field with several solar receiver
devices installed on its highest part thereof. These can be
saturated and/or superheated steam receiver devices. The steam
originating therein is pumped towards a turbine for producing
electricity.
The steam originating in the turbine and which is still very hot
must be condensed and pumped towards the receiver devices in order
to be re-used as a heat-transfer fluid.
In order to cool this steam, a system has been devised whereby the
two previously described drawbacks are overcome: the high
electricity consumption (due to the use of fans) and the large
amount of water required.
Due to the fact that the solar plant has several receiver devices
installed at great height on a tower, without need for extra
investment, our system already has the tower, which could be
leveraged as a natural-draught cooling tower. Said tower has a
series of heat exchangers, more specifically condensers, at its
base, which are in charge of condensing the steam coming from the
turbine exhaust under near-saturation conditions and evacuating the
condensation heat towards the exterior.
The fluid used to carry out this heat exchange shall be air at the
ambient temperature found at the base of the tower, which cools the
steam circulating through the condenser tube; i.e. the steam
originating in the turbine at high temperature is cooled by the air
current flowing through the condenser.
Said steam, once condensed, is pumped back towards the receiver
device in order to be re-used as a heat-transfer fluid.
The air at ambient temperature at the base of the tower, which is
responsible for lowering steam temperature, rises above the tower
due to its natural draught and exits through the highest part
thereof.
This natural circulation is also aided by the existence of a heat
source such as the receiver devices on the highest part of the
tower.
Additionally, in order to facilitate the aforementioned
natural-draught effect, the tower of the invention under discussion
has a hyperbolic and hollow structural design, in such a manner
that an ascendant air current flows therethrough to cool the steam
by natural convection.
Using the solar tower as a cooling tower, it is given a dual
function: that of accommodating the receiver devices at the
necessary height for concentrating the radiation and use as a
cooling tower.
This allows a reduction in water consumption on eliminating the
water required for the cooling circuit, as cooling is based on air
and not water, thereby avoiding the construction of additional
cooling towers and reducing the overall cost.
Additionally, in order to manage the steam produced and ensure
availability thereof in the absence of daylight hours, the plant
includes a storage system based on water/steam tanks or molten
salts.
DESCRIPTION OF THE DRAWINGS
In order to complete the description being made and with the object
of helping to better understand the invention, it is accompanied by
a set of drawings wherein, in an illustrative and non-limiting
manner, the following have been represented:
FIG. 1 shows a simplified schematic view of the cooling
circuit.
The references used herein correspond to: (1) Tower (2) Evaporators
(3) Drum (4) Superheater (5) Storage system (6) Turbine (7)
Generator (8) Condenser (9) Hot air (10) Condensate pump (11) Valve
(11') Valve (12) Condensate storage tank (13) Condensate pump
PREFERRED EMBODIMENT OF THE INVENTION
In order to better understand the cooling method disclosed in the
invention, a description of the diagram shown in FIG. 1 is provided
below.
As can be observed in FIG. 1, the evaporators (2) wherethrough
water or any other heat-transfer fluid circulates are disposed on
the highest part of the tower (1). This fluid is heated by the
solar radiation reflected thereupon by the heliostats, which are
located on the ground around the tower (1). Once the heat-transfer
fluid has flown through the evaporator (2) subjected to solar
radiation, it flows out therefrom in the form of saturated steam at
a temperature of approximately 300.degree. C. towards the drum
(3).
Separation into liquid and steam takes place inside the drum (3).
In general, the drum (3) receives the saturated steam that flows
out of the evaporator (2) and feeds the superheater (4), thereby
ensuring that it is always dry upon entering the superheater
(4).
Another part of the steam produced therein is pumped towards the
storage system (5), making it pass through a valve (11) which
ensures that it flows into said system (5) with the right amount of
pressure.
The steam which has entered the superheater (4) also receives solar
radiation reflected by the heliostats and exits at a very high
temperature of approximately 540.degree. C., allowing the turbine
(6) to work at full capacity.
In turn, the turbine (6) is connected to the generator (7), which
shall be responsible for transforming turbine (6) rotation into
electricity to be fed to the grid.
In order to leverage the steam that exits the turbine (6), it is
made to circulate through the conduits of a condenser (8) installed
in the base of the solar tower (1).
The steam will cool and condense at the same time due to the
cooling effect of the air circulating around the condenser (8). The
temperature of said air, which is air at ambient temperature, rises
on absorbing heat from the condenser (8) tubes and becomes hot air
(9), whereupon it travels up through the solar chimney or tower (1)
and is discharged to the atmosphere through the highest part
thereof.
Meanwhile, the already condensed steam that exits the condenser (8)
is pumped (10) towards a condensate storage tank (12).
When additional heat-transfer fluid is required in the evaporators
(2), a condensate pump (13) pushes the liquid stored inside the
condensate tank (12) towards these.
Therefore, consumption of water or heat-transfer fluid decreases
dramatically due both to re-use thereof and to dispensing with the
use of water for the cooling system.
It must be highlighted that the foregoing description is an example
of a preferred embodiment of the invention, but there are aspects
such as the existence of superheated steam receiver devices or a
storage system which could be dispensable and have no influence on
the disclosed cooling method.
* * * * *